[Hohenheimsenberg]

When I upgraded my system I didn't know that made a difference, I just got a new DAC without thinking about it.

But one day I was listening to music with my laptop I felt something wasn't right, I moved to my desktop which has an optical output and It sounded better. So I googled and found several post explaining the differences and remembered the little thing audio quest released a few years back.

I'm completely sure I need something to clean my signal, I just bought a new cable to see if that helps.

But if it doesn't, I'm between an Ifi ipurifier 3, a Schiit eitr and a DU-U8. All of them at the same price.

My system:
Schiit Modi multibit - Focal clear
Chord mojo (I didn't heard any difference switching between optical or USB on any headphone) - Dunu Falcon C

 

[tomb]

If I'm not mistaken, the marketing from Schiit claims that you can use the Modi without its power supply, when not using a phone or tablet - but using USB. The optical input apparently requires the Modi's power supply, no matter to what you are connecting. Unfortunately, laptop power supplies can be notoriously noisy. So, if you are connecting to the Modi using USB without its power supply operating, that's probably the explanation. The Modi is taking its power from the laptop's power transmitted through the USB cable. When you use optical, you're plugging in the Modi's own power supply.

In the case of the Chord Mojo, it probably uses its power supply in either of the cases you mention.

Interestingly, this is one reason why some of the talk about super-duper USB cables is REAL. Digital is digital, as they say, and if you get all the bits you're supposed to, it either works or it doesn't - no in-between. That's true as far as it goes, but it doesn't go as far as to address the 5VDC voltage that the USB cable also transmits. If the DAC you use is depending on USB power (no external power supply for the DAC), then that power quality - and the quality of the cable - will have a direct effect on the DAC performance quality.

 

[Hohenheimsenberg]

I always keep the power supply in the modi. I tried to tape the +5v pin in the cable and it did no longer work, probably the modi doesn't care and always takes power from the USB instead the power supply.

I was listening to the mojo yesterday with my phone, on a quiet night. I listened something I didn't listen before, it was a hissing/noise on certain frequencies and eventually some clipping. The mojo has its own battery and a different input for power, I use an OTG and a micro USB to C converter.

 

[luemas]

I have a Schiit Modi 3 and I got a cleaner signal when I plugged the USB cable into a different port on my desktop (motherboard).

I don't remember where I read this, but somewhere someone suggested using a USB 2.0 port rather than a USB 3.0 port if you're getting noise on Schiit DACs where the signal and power are both coming in through USB. I did that and it made a pretty noticeable difference! No more fuzz in the right channel.

I always keep the power supply in the modi. I tried to tape the +5v pin in the cable and it did no longer work, probably the modi doesn't care and always takes power from the USB instead the power supply.

It sounds that way to me too. Strange.